Promote specific 'additional info' fields of INFO files to strongly typed model fields.

## Background
Many fields that are present in `mtadata.additionalInfo` of a Run object or an INFO file are so useful that we want to ensure they are always populated. Currently, all these fields are optional since they reside in a key-value map called `additionalInfo`. If we make them part of INFO files / Run objects model, it will better enforce them being populated and would give better guarantees that these field names won't be changed in the future.

## Feature
The fields that should always be a part of an INFO file should be promoted to strongly typed part of the model. The list of such fields need to be discussed.

This should help to enforce better quality of INFO files (#875)

## Example [Optional]
(The list of fields to be promoted to be added here)